need larger list of DNS_SEEDS for mainnet

[garyyu]

Today all the 3 nodes in FLOONET_DNS_SEEDS i.e. floonet.seed.grin-tech.org are down and not accessible, which cause all new nodes can't connect to the Floonet.

This issue is just used to remind us that we indeed need a larger list of this DNS seed, at least 3 for example, and perhaps 6 or 8 for the initial seeds are better.

[garyyu]

For the workaround solution to "fix" this DNS issue
change the grin-server.toml config, add the following line:

peers_preferred = ["35.157.67.48:13414", "204.48.26.36:13414", "35.203.155.51:13414", "104.248.18.227:13414", "153.169.74.3:13414", "89.101.91.246:13414", "35.246.154.78:13414", "167.99.87.54:13414", "51.175.188.119:13414", "217.182.192.59:13414", "35.227.48.174:13414", "84.94.235.161:13414", "95.236.53.34:13414", "162.244.80.115:13414", "167.99.53.226:13414", "119.237.58.248:13414", "68.107.96.202:13414", "76.21.112.249:13414"]

And then restart the grin process.

[ignopeverell]

We certainly need both more seeds and more DNSs. But my seed has been up that whole time so not sure what happened?

[lehnberg]

Tried it again before applying the above fix, and it's now working as it should. 11 connected peers. ¯\_(ツ)_/¯

[antiochp]

I suspect (but have no concrete evidence) that these seed nodes were maxed out with peers.
We have 8 "preferred" and 25 max peers by default. Once we hit 25 I don't think we accept any more connections and the seed nodes will appear to be unavailable or down.
Ping (or any other ports) will be unaffected by this.

We should probably have the seeds configured to accept more than 25 max peer connections.

[yeastplume]

is it acceptable for a node to pass on the address of another known node when it’s reached its max peer limit?

[antiochp]

Peers won't know reliably how many peers other peers have... we have no insight into this (and probably shouldn't trust them even if they did broadcast this).

We should allow nodes (and the seeds) accept higher numbers of peers (even if temporarily) just to facilitate peer lists being sent around.
I'm not actually sure of the specifics of how bitcoin does this.

[DavidBurkett]

It looks like bitcoin actually allows up to 125 peers by default, although that seems a bit excessive. There is code that dynamically lowers that based on the number of available file descriptors though. https://github.com/bitcoin/bitcoin/blob/master/src/net.h

I can't find it in their bloated codebase, but if I recall correctly, there at least used to be code that would allow a peer to connect, even if you have too many connections. It would then immediately broadcast an addr message, and then disconnect. It's also entirely possible I completely made that up, or that I'm getting it mixed up with some bitcoin tools I wrote. Either way, it seems like a good idea.

[ignopeverell]

I've greatly increased the max peers on my seed yesterday (now 250). I think all seeds should do this. It may be nice later to have a peer feature that's seed only, so other peers can by default disconnect after a bit to not hold up more connections.

[superphly]

What's the process of donating a seed box? I'd be glad to add to the pool. I have several options.

[ignopeverell]

https://www.grin-forum.org/t/grin-mainnet-seeds-needed/1580

[ignopeverell]

More have been added with more coming. Closing.